盐度对海月水母幼体行为、附着和无性生殖的影响

Effects of salinity on swimming,settlement and asexual reproduction of the moon jellyfish Aurelia aurita larvae

黄渤海沿岸海参养殖池为海月水母(Aurelia aurita)幼体的重要栖息地,海参养殖池盐度波动范围极大,因此,研究不同盐度对海月水母早期生活史的影响对于理解其环境适应机制具有重要科学意义.本研究以海月水母为研究对象,探讨了不同盐度梯度(18、22、26、30、34和38)对海月水母浮浪幼虫行为、附着以及螅状幼体无性生殖的影响.结果表明,盐度对海月水母浮浪幼虫的运动行为存在显著影响,较高盐度环境(30、34和38)海月水母浮浪幼虫运动速度明显高于较低盐度环境(18、22和26);盐度对海月水母浮浪幼虫的附着有显著影响,相对较高盐度促进海月水母浮浪幼虫的附着,盐度为34时,海月水母浮浪幼虫附着率最高;海月水母螅状幼体无性生殖能适应较广的盐度范围,42d无性生殖实验周期后,18~34盐度环境下海月水母每个螅状幼体平均新繁殖螅状幼体个体数为2.8~3.7个,不同盐度处理组间无显著差异,而极高盐度(38)显著降低海月水母的出芽生殖率(1.2个).本研究表明盐度对海月水母早期生活史不同阶段幼体具有不同影响,研究结果为黄渤海沿岸海月水母环境适应机制研究提供了重要参考.

The sea cucumber( Apostichopus japonicus) culture ponds may act as a nursery ground for the moon jellyfish Aurelia aurita in the coastal waters along Bohai Sea and the Yellow Sea. Fluctuation of salinity in the A. japonicus culture ponds frequently found due to water exchange,evaporation and heavy rainfall. Therefore,it is necessary to understand the effects of salinity on the recruitment dynamics of A. aurita in their early life stages. In the present study,laboratory experiments were conducted to investigate the effects of different salinities levels( 18,22,26,30,34 and 38) on the swimming,settlement and asexual reproduction of A. aurita larvae. Our results showed that the swimming speed of A. aurita planulae was significantly influenced by the salinities. The planulae moved faster at the high salinities( 30,34 and 38) than those at the low salinities( 18,22,and 26); The settlement rates of A. aurita planulae were significantly influenced by the salinities. The highest settlement rate occurred at asalinity of 34. There was no significant difference in the bud reproduction rate between different salinities( 18 ~34). The mean new polyps produced by one polyp at the salinities between 18 and 34 were 2. 8 ~ 3. 7. The polyps incubated at a salinity of 38 produced the least polyps( 1. 2 ± 0. 6). Our results indicate that salinity have different effects on the early life stages of A. aurita. Thus the study provides new information for understanding the adaptation of A. aurita to environmental factors in the coastal waters of Bohai Sea and the Yellow Sea.